Although Thursday is the first day of the summer month of June, there's no indication of balmy summer weather in sight. Daytime highs for the month are already unusually low, said Yle meteorologist Seija Paasonen.

"Between April and May we generally have the kinds of temperatures we are seeing now," Paasonen noted.

The weather forecast puts daytime highs Thursday and Friday at a chilly 10 to 11 degrees Celsius, while highs in central regions will runs from six to 7 degrees and from two to seven degrees Celsius up north.

According to Paasonen, at this time of year, average daytime highs in Helsinki should be around 17 degrees, and even up north, highs should be above 10 degrees.

Meanwhile new data from the Finnish Meteorological Institute indicate that across northern Finland - from Kainuu in the east to northern Ostrobothnia in the west - temperatures in May were nearly three degrees Celsius below the long term average.

The last time Finnish residents experienced a May as cold as this was in 1969 - nearly 50 years ago.

May 2017: 19 degrees in Hämeenlinna, -13 in Suomussalmi

Up north, average temperatures for the month came in at two degrees. Just one year ago, the average for the region was 8.6 degrees Celsius, FMI said Thursday.

In Rovaniemi average temperatures were three degrees lower than usual - reaching just five degrees Celsius. In Savukoski, Lapland temparatures deviated from the long term average by 2.7 degrees, making the average come in under four degrees.

By comparison, the coldest place in the world, Oimjakon in Siberia has a long term average temperature of 2.7 degrees in May.

The highest daytime reading of the month came from Hämeenlinna on May 19, where local monitoring stations recorded 27 degrees. The lowest temperature was registered in Suomussalmi, east of Oulu, on May 16, when the mercury plunged to -13.1 degrees Celsius.